Elastic pivot



ELASTIC PIVOT Filed Aug. 25, 1966 2 Sheets-Sheet 1 INVENTOI /cmqeo R.ZD'QCY .47 roeA/EXS.

R. R. TRACY ELASTIC PIVOT July 30, 1968 2 Sheets-Sheet 2 Filed Aug. 25,1966 Unite States Patent O 3,394,970 ELASTIC PIVOT Richard R. Tracy,Pasadena, Calif., assignor to The Task Corporation, Anaheim, Calif., acorporation of California Continuation-in-part of application Ser. No.187,869, Apr. 16, 1962. This application Aug. 25, 1966, Ser. No. 575,898

Claims. (Cl. 308-2) This application is a continuation-in-part of mycopending application, Ser. No. 187,869, entitled Elastic Pivot, filedApr. 16, 1962, now abandoned.

This invention relates generally to elastic pivots and more particularlyhas to do with a novel elastic pivot characterized as having improvedload handling characteristics.

Devices of the general type with which the invention is concerned areused typically as limited motion pivots between a source of loading andload meters or sensing devices, for the purpose of transmitting onlyaxially imposed loading to the meters, as opposed to transmittinglaterally imposed loads. In other words, such devices may becharacterized as acting to segregate aXial from lateral loading asrespects transmission thereof to the meter. These devices find wideapplication in force measuring and weighing systems where differentmeters measure longitudinal and lateral loading and are to be isolatedfrom loading and movements other than those to be measured. The qualityof such a device is therefore dctermined at least in part by its abilityto function in this manner, and it is a major object of the invention toprovide a novel device of this type which will so function in a betteror more efiicient manner particularly as respects the amount of loadingwhich the device will handle without failure, for a given overall sizeof the device.

As broadly conceived, the improved elastic pivot comprises a body havingopposite ends longitudinally spaced apart in the direction of the bodyaxis to receive application of force, the body also having web means andbody intermediate extent for transmitting axially imposed force betweenthe body ends and in sequence through first web means, the bodyintermediate extent and finally second web means. More importantly fromthe standpoint of efiiciency of load segregation and load bearingability for a given sized unit, the first and second Web means are madeto extend in substantially longitudinal planes which are spaced from thebody longitudinal axis, extensions of these planes having substantiallyperpendicularly intersecting relation lengthwise along that axis. Inaddition, the first and second web means each comprise a pair of webs,the webs of each pair typically but not necessarily having concaveopposite faces, and preferably all of the webs have minimum thickness inor proximate a common plane perpendicular to the body longitudinal axis.As a result, the web means are adapted to flex in response toapplication to the body ends of moments acting in longitudinal planes,and in such manner that substantially only axial loading is transmittedin use through the device, the overall load handling capacity beingoptimized for a given size device.

Of particular advantage is the one-piece construction which the devicemay have due to the novel arrangement of slots, webs and recesses all ofwhich will be discussed in detail, with consequent elimination of needfor welds particularly in primary load paths or critical areas of thedevice. Other advantages fiowing from the novel arrangement of webs,slots and recesses include the reduction of manufacturing difficulties,the fixing of pivot or fiexing axes in a common plane, the ability ofthe device to carry rather large lateral forces which are applied suchas not to produce bending moments about the pivot axes, the

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predetermination of the web design to be characterized as associatedwith the ability of the webs to carry greater axially imposed loadingwithout buckling, as opposed to other designs not so characterized, andfinally the ability of the device to carry torsion moments.

These and other objects of the invention, as well as the details of anillustrative embodiment, will be more fully understood from thefollowing detailed description of the drawings, in which:

FIG. 1 is a plan view of a preferred embodiment, looking parallel to thelongitudinal axis thereof;

FIG. 2 is a side elevation view of FIG. 1 embodiment;

FIG. 3 is another side elevational view of the FIG. 1 embodiment rotatedrelative to FIG. 1, and about the body axis;

FIG. 4 is an enlarged section taken on line 4-4 of FIG. 3;

FIG. 5 is an enlarged section taken on line 5-5 of FIG. 2;

FIG. 6 is a view showing the manner in which devices of the FIG. 1 typemay be connected in load transmitting relation between a source ofloading and meters or load sensing devices;

FIGS. 7 and 8 are side elevational views like FIGS. 3 and 2, showing amodified form of the invention;

FIG. 9 is a top plan view of the FIG. 7 body; and

FIGS. 10 and 11 are enlarged Sections taken on lines 10-10 and 11-11 ofFIGS. 7 and 8 respectively.

Referring first to FIG. 6, the elastic pivot 10 is shown as connected inaxial load transmitting relation between the load source 11 and themeter 12. Axial loading is indicated by the arrow 13, it beingundcrstood that lateral loading in other directions may be imposed,arrow 14 being merely typical of one direction of imposed lateralloading. The load source might typically represent a rocket on a teststand, with the arrow 13 representing forces arising due to the aXialthrust loading imposed during rocket firing. It would then be desiredthat the meter 12 measure such loading as distinguished from lateralloading 14 arisng during rocket operation. Another elastic pivot 10a isshown at the axially opposite side of the meter 12, and other elasticpivots 10b and 10a are shown as connected in lateral load transmittingrelation to meter 12a which measures lateral loading 14.

Referring now to FIGS. 1 through 5, the unit 10 Comprises a body,typically of one-piece construction, having opposite ends 15 and 16which -are longitudinally spaced apart in the direction of the body axis17 to receive application of force. Such force may be transmitted to andfrom the body by threaded fastening means typically in the form ofthreaded studs 18 and 19 respectively pr-ojectng axially oppositely fromthe opposite ends of the body.

The body also has first and second web means respectively indicated at20 and 21 in FIGS. 3 and 2, as well as body intermediate extent 23 fortransmitting the bulk of axially imposed force between the body ends andin sequence through the first web means 20 as indicated by the arrow 24,then through the body intermediate extent as ndicated by the arrows 25in FIG. 3, and then through the second web means 21 as indicated by thearrow 26 in FIG. 2. As shown in FIG. 5, the first web means maytypically but not necessarily comprise a first pair of webs 27 which arespaced apart at opposite sides of the body longitudinal axis 17, and thesecond web means may typically but not necessarily comprise a secondpair of webs 28 spaced apart at opposite sides of the axis 17. The twowebs 27 extend in a common plane having an extension 29 which intersectsthe axis 17 along its length, and also the two webs 28 extend in acommon plane having an extension 30 which intersects the axis 17 as wellas the extension 29. In other words, the extensions 29 and 30 havesubstantially perpendicularly intersecting relation lengthwise along theaxis 17 as shown in FIG. 5. In this regard, it will be observed in FIGS,2, 3 and 4 that the body means has rigid beam portions 31 and 32 throughwhich loading is transmitted between the body opposite ends and 16 andthe web means and 21.

Further in connection with what has been described, the one-piececonstruction of the body is facilitated by the provision of four pairsof recesses 33, the recesses of each pair being located at transverselyopposite sides of a web such as has been described. These recessesextend from the cylindrcal outer side of the body to the body interiorwhere they intersect as best seen in FIG.. 4.

Furthermore, the recesses are each generally cylindrical, and areconfined between a pair of longitudinally spaced apart parallel planes34 and 35 perpendicular to the axis 17 as seen in FIGS. 2 and 3. Thus,the recesses have equal longitudinal extent, and the recesses of eachpair are so formed that the web between the recesses has minimumthickness between concave opposite faces such as are shown at 36 and 37in FIG. 3. Accordingly, a common plane 44 perpendicnlar to the axis 17intersects the webs at or near their minimum thickness points, the plane44 being typically but not necessarily equidistant from opposite ends 15and 16 of the body.

The body also contains two pairs of slots, the first pair of slots beingshown at 39 in FIG. 3, and the second pair Abeing shown at 40 in FIG. 2.Slots 39 extend from the outside of the body near its end 15 intocommunication with the recesses 33 at opposie sides of the first we-bmeans 20, whereas the second pair of slots 40 extend from the outside ofthe body near its end 16 thereof into communication with the recesses 33at opposite sides of the second web means 21. As shown, the slots 39extend in planes which taper or converge generally toward the first webmeans 20, whereas the slots 40 extend in planes which taper or convergegenerally toward the second web means 21. Accordingly, the rigid beamportions 31 and 32 are formed between the respective pairs of slots 39and 40. As a result of the aforesaid construction, advantage is taken ofthat design which is associated with the ability of the web means tocarry maximum axial loading without buckling. At the same time, it willbe observed that the webs are adapted to flex in response to applicationto the body ends of moments acting in longitudinal planes parallel tothe body axis 17.

Referring now to FIGS. 2 through 4, it will be seen that a pair of stopmembers, as for example pins 41, extend transversely and in parallelrelation through bores 42 formed in the rigid beam portions 32, withclearance between the pins and the bores. The end portions of the pinsare retained within the body intermediate extent 23 at transverseopposte sides of the portion 32. As a re- I sult, pivoting or defiectionof the rigid beam portion 32, as accommodated by flexing of the webmeans 21, is stopped by engagement of the bores 42 with the pins 41before such defiection closes either of the slots 40. A correspondingpair of pin members 43 are shown in FIG. 3 as extending through bores 44in the rigid beam section 31, with clearance between these pin membersand bores 44. The function of the pins 43 is the same as described inconnection with pins 41, that is to stop deflection of the section 31 asaccommodated by fiexing of the web means 20, before such deflectioncloses either of the slots 39. Alternately, the'clearances may beenlarged to permit closure of the slots before stopping on the pins, thepins then serving as Safety devices to prevent complete separation ofthe end portions in the case of Web failure.

FIG. 4 also shows a longitudinal central bore 45 through the fasteningmeans 19 and extending beyond the central plane 44. This boreconveniently forms the central space at opposite sides of which the websextend, as illustrated, and thereby facilitates one-piece manufacture ofthe device.

FIGS. 7-11 show a modified form of the invention in which the one-piecebody is in the form of a block, with rounded edges 101, and havinglarger and heavier sections 102 than appear in the FIG. 5 cross-section.As a result the body will handle greater loading. Also, the threadedfastening means 103 at one end of the body is in the form of aninteriorly threaded sleeve. Note that the recesses 33 are spaced Closerto body end 104 than -body end 105, to facilitate the wider spacingbetween the terminals of slots 40 at body end 105 than between theterminals of slots 39 at body end 104, such wider spacing accommodatingthe larger Chamber sleeve 103. Otherwise, the construction of the FIG.7-11 device is like that the of the FIG. 1-6 device, with correspondingparts having the same numerals.

I claim:

1. An elastic pivot coniprising body means having opposite endslongitudinally spaced apart in the direction of the body axis to receiveapplication of force and having first and second web means and bodyintermediate extent proximate thereto for transmitting axially imposedforce between said ends and in sequence through first web means, saidbody intermediate extent and second web means, said first and second webmeans extending in substantially longitudinal planes disposedsubstantially at right angles to each other and which are spaced fromsaid axis, extensions of said planes having substantiallyperpendicularly intersecting relation with each othor lengthwise alongsaid axis, said web means Abeing adapted to flex in response toapplication to said -body ends of moments acting in longitudinal planes,the body containing transversely drilled substantially circular crosssection recesses at oppose sides of each web means so that the web meanshave concave faces adjacent said recesses, the recesses at oppositesides of the first web means extending toward and terminating near thesecond web means so as to be interiorly blocked by the second web means,the other recesses at opposite sides of the second web means extendingtoward and terminating near the first web means so as to be interiorlyblocked by the first web means.

2. The pivot of claim 1 in which the body means is of one piece and hasrigid transverse beam portions through which loading is transmittedbetween said ends and said webs, the body means containing an axial borepenetrating from within one of said beam portions into a locusintermediate the inner terminals of both said first and second web meansto completely free said locus of body material.

3. The pivot of claim 1 in which said first web means comprises a firstpair of webs spaced apart at opposite sides of said axis, and saidsecond web means comprises a second pair of webs spaced apart atopposite sides of said axis.

4. The invention as defined in claim 3 in which all of said webs haveminimum thickness in a common plane perpendicular to said axis.

5. The invention as defined in claim 4 in which said common planebisects said body midway between said opposite ends thereof.

6. The invention as defined in claim 3 in which the body contains twopairs of slots, the slots of the first pair extending from one end ofsaid body into communication with the recesses at opposite sides of saidfirst pair of webs, and the slots of the second pair extending from theopposite end of said body into communication witll: the recesses atopposite sides of said second pair of we s.

7. The invention as defined in claim 6, in which the body has transversebeam portions, and including fastenmg means respectively projectingaxially oppositely from the transverse beam portions of the body betweensaid pairs of slots.

3,394,970 5 6 8. The nvention as defined in claim 7 in which theReferences Cited slots of each pair converge axially toward the recesseswith which the slots communicate. UNITED STATES PATENTS 9. The inventionas defined in clairn 7 including mem- ;966,049 12/1960 Ormond 287 85 XRbers secured to body extent other than said transverse 5 2,969,6561/1961 Reur 287 85 XR beam portions, said members extending into suchprox- 3,169,613 2/1965 Webb 64-15 XR imty to said portions thatdeflection of a transverse beam portion will be stopped Iby at least onemember before MARTIN p SCHWADRON, Primary Examner. said deflectioncloses any slot adjacent said `|portion.

10. The pivot of claim 1 in which the body is of 10 ROBERT R. BUNEVICH,Assistant Examirzer.

substantally block form.

1. AN ELASTIC PIVOT COMPRISING BODY MEANS HAVING OPPOSITE ENDSLONGITUDINALLY SPACED APART IN THE DIRECTION OF THE BODY AXIS TO RECEIVEAPPLICATION OF FORCE AND HAVING FIRST AND SECOND WEB MEANS AND BODYINTERMEDIATE EXTENT PROXIMATE THERETO FOR TRANSMITTING AXIALLY IMPOSEDFORCE BETWEEM SAID ENDS AND IN SEQUENCE THROUGH FIRST WEB MEANS, SAIDBODY INTERMEDIATE EXTENT AND SECOND WEB MEANS, SAID FIRST AND SECOND WEBMEANS EXTENDING IN SUBSTANTIALLY LONGITUDINAL PLANES DISPOSEDSUBSTANTIALLY AT RIGHT ANGLES TO EACH OTHER AND WHICH ARE SPACED FROMSAID AXIS, EXTENSIONS OF SAID PLANES HAVING SUBSTANTIALLYPERPENDICULARLY INTERSECTING RELATION WITH EACH OTHER LENGTHWISE ALONGSAID AXIS, SAID WEB MEANS BEING ADAPTED TO FLEX IN RESPONSE TOAPPLICATION TO SAID BODY ENDS OF